We will start by working with a simple model of a single random tripartite tensor, which turns out to be perfectly tractable analytically. It models a three-boundary wormhole with horizon areas fixed to a small window [1]}, [2]}, [3]} and a large interior. This results in an entanglement wedge (EW) phase transition as we tune the bond dimensions (the horizon areas). The “Page curve” for such a transition has the characteristic jump in reflected entropy shown in fig:analyticphasetransition. We then work with hyperbolic tensor networks, where the results are harder to control. Nevertheless, we extrapolate lessons from the simpler models (since they show many similarities with the larger networks) to compute the reflected entropy in these models as well.
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